Hydraulically operated mine roof supports



HYDHAULICALLY OPERATED MINE ROOF SUPPORTS E "a 75 78a \78 7` V0 A A nventorS :T0 H N D EL SE JOHN ML By 'Hdwg Attorney 5 5 Sheets-Sheet 2 Inventor;-

J. D. ELSE ET AL JOHN D. ELSE 35C rd HYDRAULICALLY OPERATED MINE ROOF SUPPORTS :roHN w. GRAN-r By/Qmd- Attorneys Dec. 2, 1969 Filed July 28, 1967 l Dec. 2, '1969 J, D "LSE ET AL 3,481,573

. HYDRAULICALLY OPERATED MINE ROOF SUPPORTS Filed July 28, 1967 3 Sheets-Sheet 3 a 70 :gg 62a -54 ,67 6 53 62 yk 72a Inventor;

JOHN D. ELSE zroHN w. GRANTBy/O uw A Horne ys United States Patent O U.S. Cl. 248-357 6 Claims ABSTRACT OF THE DISCLOSURE The leg of a mine roof support, which is liable to be diverted from its proper vertical position under working conditions, is provided with a form of loading device at the foot of the leg, which while it is capable of a limited amount of tilting movement when the leg is diverted, will act to restore the leg to its vertical position when the force which has given rise to the tilting is released.

BRIEF SUMMARY OF THE INVENTION The leg is tiltably mounted on its base in such a way that it can be tilted to a certain extent under load, but means such as a spring or a fluid-pressurized piston is so mounted at the foot of the leg that when the force which has given rise to the tilting is released the spring or 'the piston, as t-he case may be, will assert itself and. restore the leg to the proper vertical position.

-This invention relates to hydraulically operated mine roof supports.

The invention is concerned with the type of support which includes upstanding legs mounted on a fbase, and it is found in practice that under load these legs tend to be diverted from a truly vertical position due to relative movement between roof and floor. In some cases they are mounted in rubber or similar exible locations in boxes at the base, but under working conditions the rubber can become tired and is often unable to restore the legs to their proper position when they are released from the roof. Consequently, the legs may be distorted or damaged.

The object of this invention is therefore to provide an improved form of mounting for such legs which will allow them to be deflected suiiiciently from the vertical position without damage, and will act automatically to restore them immediately to their true vertical or preset position as soon as they are relieved of the load.

According to the present invention the leg is tiltalbly supported upon a base member so that the leg can be deflected iby an adequate amount from the vertical, loading means being operatively associated with the lower end region of the leg, the loading means being so organised as to yield to the deflecting movement of the leg, and to act in restoring the leg to the vertical position upon release of the load which has given rise to the deflection.

In a preferred arrangement the leg is tiltably supported on a base member and a pre-compressed coil spring is fitted inside the bottom end of the leg and clamped in position so that it permits an adequate amount of deflection of the leg from the vertical but eventually becomes solid, the spring acting to restore the leg to a vertical position on release of the load.

-Preferably the spring is tted roundV a bolt or stud and located at one end by a member shaped to allow Patented Dec. 2, 1969 ice a limited amount of tilting action by virtue of a chamfered face on the member which co-operates with a nontiltable level surface on the base member.

In an alternative arrangement the lower end of the tubular leg contains a hydraulic cylinder and the head of a piston in the cylinder forms a support for the spherical foot of a plunger whose head carries a disc or plate having a rounded perimeter fitting in the bore of the leg.

Preferably the upper face of the foot of the plunger is forced upwards against a shoulder in the hydaulic cylinder by the hydraulic pressure which serves to hold the foot in place in the cylinder.

In operation When the leg tilts, the plunger is tilted with it and the spherical foot depresses the piston against the hydraulic pressure. As soon as the leg is released from the roof the piston will push against the spherical surface of the foot and restore it to a central position with the plunger therefore upright. The disc or plate attached to the plunger imparts a corresponding movement to the leg itself and the leg is thereby automatically restored to the vertical position again.

Constructional forms of the invention will now be described with reference to the accompanying drawings in which:

FIGURE l is a sectional elevation showing a base assembly and the lower end portion of a leg, with the leg in a vertical position.

FIGURES 2 and 3 are similar views to FIGURE 1 showing the parts in the alternative positions of partial deflection and maximum 'deflection respectively.

FIGURES 4, 5 and 6 are similar views to FIGURE 3 showing three alternative constructions, each in a position of maximum deflection.

Referring to FIGURES l, 2 and 3 the base 10 of the roof support has a member 11 secured to it by means of screws 10a; the member 11 has a flat level upper surface 11a forming a seating for the tubular leg 12. The bottom end of the leg has an encircling horizontal flange 12a and a bottom plate 13 is attached by screws 12b to the ange. The plate has a central opening 14 which receives a bush 15 which projects upwardly and is a close iit in the opening. The central portion of the plate immediately around the opening 14 rests flush on the flat surface of the seating 11a but the outer portion of the plate is radially and upwardly charnfered to a vsuitable angle, possibly about 7, as shown at 13a, so that the plate 13 (and hence the leg 12) can rock on the seating 11a. FIGURE 3 shows a position of approximately 10 maximum deflection, A bolt 17 (or a stud with nut) is inserted through the hole in the bush 1'5, a Washer 18 being iitted on the bolt; the upper surface of the Washer is spherical as shown at 18a and the bush 15 has a conical upwardly and inwardly tapering internal face 15a resting on the spherical surface 18a of the washer. Above the bottom plate 13 of the leg 12 but inside the bore of the leg a strong coil spring 20 is iitted with the bolt passing through it, and the upper end of the spring bears against a clamping plate 21 which is fitted on to the upper end of the bolt and tightened by a lock nut 22 and a washer 23 similar to the one at the lower end of the bolt, so that the spring is compressed. The underside of the clamping plate 21 has an annular projection 21a locating the upper end of the spring 20. When the leg is deflected from its vertical position under load, the chamfered bottom plate will rock on its seating as shown in FIGURE 2. This will compress the preloaded spring still further and at a suitable angle of tilt as shown in FIGURE 3, the effective couple acting on the leg by the spring is doubled and further deflection is resisted by the spring becoming solid, that is to say coil bound. As soon as the load is relieved the spring will re-assert itself and restore the leg to its vertical position as shown in FIGURE l.

FIGURE 4 shows an alternative arrangement in which a base assembly is provided in the form of a housing containing a spring 31 and stud 32. The housing 30 has a flange 33 to which is secured by screws 33a a top cover plate 34 forming a seating for a rocking member 35 attached to the flange 12a on the legs 12 by screws 12b. The member 35 has a depending boss 35a which tits into an opening 34a in the plate 34. It is also provided with a chamfered face 35b corresponding to the face 13a on the member 13 shown in FIGURES l, 2 and 3. The upper portion of the rocking member 35 forms a conical -seating 35C for the spherical portion 36a of a washer 36 at the upper end of the stud 32. The lower end of the stud has a similar washer 38 which engages with a clamping plate 39, so that the spring 31 is compressed between the clamping plate 39 and the plate 34, by the action of a nut 40 tted on to the lower end of the stud 32. The upper washer 36 is tightened up by a nut 41 on the upper end of the stud 32. The leg is shown in a fully deflected position from which it will be restored to the vertical by the spring action when the load is relieved.

Referring to FIGURE 5, the leg 12 is provided with a bottom plate which ts into the bottom end of the leg and has an outwardly extending flange portion, to which a rocking member 46 chamfered at 46a is secured by screws 45a. The plate 45 is recessed at 451) on its underside. The member 46 has a central opening 47 which is shaped to provide a conical seating 47a; a stud 48 is provided with part-spherical enlarged ends 48a, 48b, of which the upper one 48a engages with the seating 47a while the lower one 4812 engages with a corresponding conical seating 49a on a clamping plate 49 which has a central opening 50 to allow the stud 48 to pass through. A series of disc-type springs 51 mounted in a holder 52 is held in place around the stud 48 between the clamping plate 49 and a top cover 53 of a housing 54. The housing has a locating ring 55 supported on a sleeve 56 and the cover 52 is secured to the ring 55 by screws 57. The leg 12 is shown in its fully deliected position and it will be seen that when the deflecting load is relieved the spring action will restore it to a vertical position, as in the previously described constructions.

Referring to FIGURE 6, a base plate is fitted with an upstanding central spherical formation 61. A seating ring 62 rests on the spherical formation and has an upstanding inner flange 62a. The tubular leg 12 has a bottom ange 12a which is secured to the seating ring by screws 63 and the ange 62a on the seating ring projects upwards inside the bottom end of the leg 12. The spherical formation is of annular shape and the opening which it defines forms a location for a hydraulic cylinder 64 extending upwards inside the leg. The lower end of the cylinder is closed by means of a cover plate 65 which is fitted with a seal 66 so that it seals the bottom end of the cylinder. A packing block 67 in the cylinder rests on the cover plate `65. A piston 68 works in the upper part of the hydraulic cylinder and a seal 69 is rclamped between the lower face of the piston and a clamping plate 70 secured to it by a central screw 71. Hydraulic uid is admitted into the cavity 72 in the cylinder under the clamping plate to lift the piston. A plunger 73 is held in position inthe cylinder above the piston by means of a shoulder 74 in the cylinder against which the top face 75a of an enlarged foot 75 on the plunger is forced by the hydraulic pressure. The foot has a spherical lower face 75b against which the piston head bears. The plunger has a stem 76 extending upwards through the cylinder head into the bore of the tubular leg and a plate or disc 77 attached to the stem by a screw 78 and having a radiused perimeter which ts closely in the bore. lIn this arrangement again the leg 12 is shown in a fully deected position; on relief of the load the hydraulic pressure will act in a similar manner to the spring action in the previous examples, lifting the piston 68 and straightening up the plunger 73 which in turn by means of the disc 77 restores the leg 12 to its vertical position.

It will be convenient to connect the aforesaid pressure cylinder hydraulically with the advancing ram of the roof support system, so that as the roof supports are pulled by the ram each leg in the system will be returned tothe vertical position by the hydraulic operation of its restoring device.

The fulcrum point which is in fact a diameter about the center line of the leg is arranged to Vgive sufficient righting moment without causing too great an off centre loading on the leg when under roof load. rIhe fulcrum point on the outer diameter provides an increased righting moment and ability for the unit to withstand greater external moments when subjected to misuse, Such as can occur when the beam encounters a roof projection when the support unit or chock is being advanced.

In a further modification the construction shown in lFIGURES l, 2 and 3, or FIGURE 4, or FIGURE 5, are adhered to except that the spring is replaced by a block of rubber or rubber-like material, usually of cylindrical shape, with or without metal inter-leang.

The normal rubber exible leg mounting tends to be far from positive, the effectiveness of which is aggravated by the hysteresis of rubber. If rubber or the like is used as the loadin-g means, this can be pre-loaded because it is deected in the same direction irrespective of the direction of tilt of the main leg.

We claim:

1. A hydraulically extensible mine roof support apparatus having a base member, a hydraulically extensible leg supported on said base member, a central stud-like member connecting said leg to said base member, means permitting tilting of said leg relative to said base member and including a level upper surface on said base member and a chamfered lower surface on said leg and overlying said level base surface, which surfaces engage when said leg is tilted, and spring means opposing the tilting movement of said leg, said spring means opposing the tilting of said leg under load and acting to restore said leg to a vertical position when hydraulic pressure is relaxed to release said leg from its load-bearing engagement with the roof.

2. A hydraulically extensible mine roof support apparatus according to claim 1 wherein said spring means is a single coil spring tted round said stud-like member, said spring permitting an adequate amount of deflection of said leg from the vertical but eventually becoming solid, and acting to restore said leg to its vertical position when said leg is released from its load-bearing engagement with the roof.

3. A hydraulically extensible mine roof support apparatus according to claim 1 wherein said chamfered surface is formed on a rocking member attached to the lower end of said leg, the underside of said rocking member having a central aperture, a ilat level lower face surrounding said aperture and providing a ush-tting surface adapted to rest on said level surface of said base member when said leg is vertical, said chamfered surface surrounding and extending upwardly from said iiat level lower face of said rocking member and hence permitting a limited rocking movement of said rocking member and hence also the tilting movement of said leg, said studlike member passing through said aperture in said rocking member and connecting said leg with said base member, and said spring means being arranged around said stud-like member.

4. A hydraulically extensible mine roof support apparatus according to claim 1 wherein said base member is formed as a housing within which housing said spring means is located, and including a cover plate on said housing and a rocking member attached to the lower end of said leg and formed with said chamfered surface, said rocking member being tiltably supported on said cover plate.

5. A hydraulically extensible mine roof support apparatus according to claim 1 wherein said leg has a hollow lower end region therein within which said spring means is located.

6. A hydraulically extensible mine roof support apparatus according to claim 5 wherein said stud-like member extends into said hollow lower end region of said leg and said spring means is a single coil spring located around said stud-like member and clamped in position under compression.

References Cited UNITED STATES PATENTS 1,266,152 5/ 1918 Poole 40--145 1,679,623 8/ 1928 Olsen 40--145 1,681,026 8/ 1928 Bradnack 248-160 FOREIGN PATENTS 1,375,878 9/1964 France.

785,470 10/ 1957 Great Britain.

ROY D. FRAZIER, Primary Examiner FRANK DOMOTOR, Assistant Examiner 

